The overall objective of the research is the same as described in the original application: to combine a genetic with a biochemical approach to work out the intracellular pathway for the synthesis and assembly of the proteins forming the plasma membrane of mammalian cells. Towards the end, in the past year, we have begun to concentrate our efforts toward identifying and quantitating by immunological and radiobiochemical methodologies, the D and K polypeptides specified by the H-2 locus on mouse chromosome 17. We are isolating these proteins from macrophages, lymphocytes, thymocytes, and hepatocytes of different mouse strains. We are examining the cellular distribution of these membrane glycoproteins among the different subcellular fraction of these cells using both conventional cell fractionation techniques and metabolic vs. external labeling methods. We are examining the turnover of these proteins relative to the other proteeins of the membranes in which the H-2 glycoproteins reside. We are also examining different mouse strains for quantitative variation among the H-2 products.